![]() ![]() It is about 30cm long, and is attached mid-dorsally to bodywall by mesenteries.Small intestine is a long, coiled and narrow tube.Stomach serves for storage as well as digestion of food.Pyloric valve is a circular ring like sphincter muscle.Pyloric valve guards its opening into small intestine.The pyloric end of stomach is slightly constricted.These glands secrete the enzyme pepsinogen and unicellular oxyntic glands, secreting hydrochloric acids.Its mucous epithelium has multicellular gastric glands.It allows the distension of stomach when food is received.Several prominent longitudinal folds are present in the inner surface of the stomach.The posterior part is short and narrow.The anterior part is large, and broad.It is around 4 cm long, broad and slightly curved bag or tube with thick muscular walls.It is attached to the dorsal bodywall by a mesentery termed as mesogaster.Stomach is present on the left side in the body cavity.Oesophagus enlarges to join with stomach in the peritoneal cavity.An alkaline digestive juice is secreted by the glandular lining of oesophagus.During the passage of food, its expansion is allowed by longitudinal foldings.Its mucous epithelial lining is folded longitudinally and contains some mucous glands.Oesophagus is a short, wide, muscular and highly distensible tube.Gullet is the wide opening that leads to Oesophagus.Now, the pharynx tapers behind to lead to esophagus through the gullet.In male frogs, on the floor of pharynx, the small opening of a vocal sac is present on either side near the angle of two jaws.This aperture opens into the middle ear.A wide eustachian aperture is present on either lateral side in the roof.The glottis leads to the laryngo-tracheal chamber.Glottis is a longitudinal slit like aperture.A median elevation on the floor carries the glottis.So, sometimes these are termed as single bucco-pharyngeal cavity.Posteriorly, the buccal cavity reaches short pharynx without any clear demarcation.This causes the orbits to bulge inwards which in response pushes the food towards the pharynx.In course of swallowing the food, frog depresses the eyes.These areas are the bulging of eye balls. The roof of buccal cavity shows two large oval and somewhat pale areas, behind the vomerine teeth. ![]() By these internal nares, the nasal cavities open into buccal cavity.Just in front of vomerine teeth, the roof of buccal cavity contains anteriorly, a pair of small openings of internal nares.The change of pressure in large sublingual lymph sac causes the protrusion of tongue.The slimy surface of tongue facilitates in capturing the prey.This free end can be flicked out and retracted immediately after catching the prey.The anterior end of tongue is attached to the inner border of lower jaw.In frogs, tongue is large, muscular, sticky and protrusible.It is filled with a soft nourishing pulp, containing connective tissues, blood vessels, nerve and odontoblast cells that produces new material for the growth of tooth.Tooth contains a central pulp cavity open at the side.Enamel is a very hard, resistant and glistening substance.It is made up of dentine (a hard ivory-like substance), which is traversed by numerous fine canals or canaliculi.But teeth are attached to the jaw bone by a broad base made of a bone-like substance.The nature of teeth is homodont (similar), acrodont (not set in a socket).The function of teeth is to simply hold the prey and prevent it from slipping out.Vomers (two small bones in the roof of the mouth) also consists of two groups of vomerine teeth.However, teeth occur in a row of either side on the premaxillae and maxillae bones of the upper jaw.These mucous glands secrete mucus that helps in lubricating the food.It has ciliated columnar epithelial lining that contains mucous glands.Buccal cavity is large, wide and shallow.it can move up and down to close or open the mouth. Two bony jaws bound the mouth, and the jaws are covered by immovable lips.It extends from one side of the snout to the other. It is the beginning to the alimentary canal.Digestive system consists of digestive tract or alimentary canal along with the associated digestive glands.Digestive system of frog: Anatomy and Physiology of digestion Digestive system of Frog: parts and functions ![]()
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